Transformer

ABSTRACT

A transformer comprising an insulating body between the relatively parallel coil formers, said body being formed by a rectangular plate having upright edges on either side, the edges located in the core frame being slipped into incised parts of the coil former flanges.

0 United States Patent 1 62,305

Van Der Linden et al. 1 May 9, 1972 [54] TRANSFORMER [72] Inventors: Peter Martinus Cornelis Van Der Linden; [56] References Cited Hans Hubert Hakkenberg Van Gaasbeek, both of Emmasingel. Eindhoven, Nether- S lands 3,039,042 6/1962 Chatterton ..336/844 [73] Assigneez U.S. PhlllpS Corporation, New York, N.Y. Primary Exammer E- A. Goldberg [22] Filed: Jan. 28, 1971 AnorneyFrank R. Trifari [211 Appl. No.: 110,479 ABSTRACT A transformer com risin an insulatin bod betwe n the 30 F A u t Pn t n P g g Y e orelgn pp ca "m on y am relatively parallel coil formers, said body being formed by a Feb. l8,1970 Netherlands ..7002230 lar late having upright edges on either side, the edges located in the core frame being slipped into incised 336/220 parts of the coil former flanges. [51] Int. Cl ..H0lf 15/04 [58] Field of Search ..336/84, 220 2 Claims, 4 Drawing Figures TRANSFORMER This invention relates to a transformer comprising a closed ferromagnetic core having at least two parallel limbs which are surrounded by flanged coil formers.

This type of transformer may be employed in apparatus for charging batteries for use in shaving apparatus. Since the lowvoltage side of the charging apparatus can be touched and the apparatus is usually not protected by an earth contact, it is very important to guarantee a very satisfactory insulation between the primary and secondary sides of the transformer. The prescriptions for approval of such transformers require the shortest path from the primary side to the secondary side both through the air and along insulating faces to be about mm at a minimum.

An object of the invention is to provide a structure which satisfies requirements and which can be manufactured in mass at low cost. According to the invention this is achieved by providing the flanges of two adjacent coils on the side of the flange facing the other coil former with an incision parallel to the plane of the flange and by arranging between the two adjacent coils an insulating body constituted by a plate provided at least at two edges with strips, which are integral with the plate and the planeof which is at right angles to the plane of the plate, said body being arranged so that the strips along the two edges of the plates extend parallel to the flanges and fall into said incisions.

The invention will be described more fully with reference to the accompanying figures, in which:

FIG. 1 is a side elevation of one embodiment, the insulating body being partly broken away;

FIG. 2 is a perspective view of part of one of the coil formers ofFIG. 1, and

FIGS. 3 and 4 are an elevation and a sectional view respectively of the separate insulating body.

The transformer shown in FIG. 1 comprises a closed ferromagnetic core 1 formed by two C-shaped halves 3 and 5. The transformer comprises furthermore two coil formers 7 and 9 composed of a synthetic resin, on which the primary and secondary coils 11 and 13 are wound. The electric connections of the coils 11 and 13 are not shown for the sake of clarity. Each of the coil formers 7 and 9 is provided with two flanges 15 formed integrally therewith. Apart from holding the coils 11 and 13 in place these flanges serve for prolonging the leakage path between these coils on the one hand and the core I on the other hand. Without further precautions the shortest leakage path extends from each of the coils 11 and 13 around the flange edge located inside the core frame towards the core (see, for example, the arrow 19 drawn in broken line at the flange in FIG. 2). There is furthermore a short path across the air from the primary coil to the secondary coil (see the arrow 21 indicated in broken line in FIG. 1). With the practical dimensions of transformers of a few Watts of power, the two paths are too short for satisfying the prescriptions for approval.

In order to prolong said leakage paths l9, incisions 23 are made, as will be seen from FIG. 2, in the side of the flange 15 facing the other coil former. In order to cut off the path 21 across the air an insulating body 25 is arranged between the two coils 11 and 13. This body (see also FIGS. 3 and 4) is fonned by a plate 27, which is surrounded along at least two edges, in the present case along the four edges, by strips 29, 31, 33, which are integral with the plate and which are anywhere at right angles to the plane of the plate 27. The whole body 25 is moulded as a single piece from a synthetic resin. The body 25 is arranged between the coils l1 and 13 so that the plate 27 forms a partition between the coils 11 and 13 and two of the strips (31 and 33) fall into the incisions in the flanges.

By taking these precautions the shortest leakage path of the coil 13 to the core extends along the edge of the flange 15 not provided with an incision. This leakage path is indicated in FIG. 2 by the arrow 35 drawn in broken lines. If desired, this leaka e ath ma be further rolon ed b rovidin the flan e 5 on its side reriiote from tli e coil 73 (iri BIG. 2 th e top fac with a strip 37, 39, 41, which is integral therewith and which is at right angles to the plane of the flange and is formed so that the three parts 37, 39 and 41 mainly constitute prolongations of the three walls of the coil former 7 located beyond the core window, the parts 37 and 41, however, extending further to the edge of the flange 15.

A variant of the embodiment described above is obtained by omitting the strips 29. In order to prevent the leakage path from becoming too short, it is desirable to make the body 25 broader than the flanges 15 so that it extends sideways beyond the flanges.

The larger the transformer, the smaller is the laterally projecting portion of the insulating body as compared with the dimensions of the transformer, so that this variant is especially appropriate for somewhat larger transformers.

What is claimed is:

l. A transfonner comprising a closed ferromagnetic core having at least two parallel limbs which are surrounded by first and second coil formers, respectively, having flanges, two adjacent coils mounted about said coil formers, the flanges of said coil formers being provided on the sides thereof facing the other coil former with an incision parallel to the plane of the flange, an insulating body arranged between the two adjacent coils, said insulating body being formed by a plate which is provided along at least two edges with strips which are integral with the plate and whose plane is at right angles to the plane of the plate, said body being arranged so that the strips are parallel to the flanges along two edges of the plate and fall into said incisions.

2. A transformer as claimed in claim 1, characterized in that the insulating body is provided on all sides of the plate with strips which are integral therewith and which are at right angles to the plane of the plate. 

1. A transformer comprising a closed ferromagnetic core having at least two parallel limbs which are surrounded by first and second coil formers, respectively, having flanges, two adjacent coils mounted about said coil formers, the flanges of said coil formers being provided on the sides thereof facing the other coil former with an incision parallel to the plane of the flange, an insulating body arranged between the two adjacent coils, said insulating body being formed by a plate which is provided along at least two edges with strips which are integral with the plate and whose plane is at right angles to the plane of the plate, said body being arranged so that the strips are parallel to the flanges along two edges of the plate and fall into said incisions.
 2. A transformer as claimed in claim 1, characterized in that the insulating body is provided on all sides of the plate with strips which are integral therewith and which are at right angles to the plane of the plate. 